Production of trichloroethylene and tetrachloroethylene



1 Jan. 31, 1967 L. TIGANIK ETAL 3,301,910

PRODUCTION OF TRICHLOROETHYLENE AND TETRACHLOROETHYLENE Filed Feb. 11, 1964 HCI +02 INVENTORS Leonh axcL Tl gomfk Jam Sven Ra mar OMSon /PWJWN &, PM

ATTORNEYS 3,301,910 PRODUCTION OF TRICHLOROETHYLENE AND TETRACHLOROETHYLENE Leonhard Tiganik, Skoghall, and Jan Sven Ragnar Ohlson, Karlshamn, Sweden, assignors to Uddeholms Aktiebolag, Uddeholm, Sweden, a company of Sweden Filed Feb. 11, 1964, Ser. No. 344,104 Claims priority, application Sweden, Feb. 22, 1963, 1,978/ 63 6 Claims. (Cl. 260-654) The present invention relates to a method for the production of trichloroethylene and tetrachloroethylene by a reaction between copper chloride and acetylene.

Trichloroethylene and perchloroethylene are compounds that have been known for a long time and are produced on an industrial scale, usually with acetylene and chlorine as raw materials. The first step in the production of trichloroethylene is the production of tetrachloroethane, which is obtained by addition of chlorination of acetylene with chlorine. For obtaining trichlorethylene the tetrachloroethylene is then treated with lime or thermally cracked. As a by-product is obtained calcium chloride or hydrogen chloride respectively.

Tetrachloroethylene is produced from trichloroethylene by reaction with pentachloroethane or by direct.

chlorination of acetylene in a gas reaction at 400500 C.

It is known to chlorinate acetylene with cupric chlo-.

ride for instance from the German Patent Specification No. 1,011,414, which refers to a method for producing 1,1-dichloroethylene and trans-1,2-dichloroethylene by reaction between acetylene and hydrogen chloride in the presence of cupric (II) and cuprous (1) ions in a ratio of from 1:4 to 1:9. It is also known to produce vinylchloride, dichloroethylenes, monovinylacetylene, etc., from acetylene, hydrogen chloride and copper chlorides. It is common for all these known methods to work in strongly acidic solutions and with a high content of enprous (I) ion in relation to cupric (II) ion.

It has now surprisingly been found that the chlorination of acetylene with cupric chloride gives high yields of trichloroethylene and tetrachloroethylene if the acetylene is carried through a reaction solution containing cupric and cuprous ions, where the amount of cupric ions is 50-100 mole percent of the total copper amount, the pH value of the reaction solution being kept at 1-3, preferably 1-2.5, and the temperature of the reaction solution being kept at at least 60 C. pH is here a value measured with a glass electrode. In all pH measurements a sample of the reaction solution is diluted with an equal part of distilled water. Often the reaction solution has been so concentrated, that a dilution has been necessary for carrying out the measurement without crystallization of the solution. Of course it is improper to speak of pH in a solution having the. high ionics strengths here used, but the values obtained are well reproducible from case to case.

In the used reaction solution the l-valent copper may be oxidized to 2-copper with chlorine or with hydrogen chloride and oxygen, for instance in the manner described in German Patent No. 1,094,734 and Swedish Patent No. 178,849. The possibility of utilizing hydrogen chloride as a chlorine source is .valuable, as hydrogen chloride is obtained as a by-product in many chlorination reactions.

Trichloroethylene and tetrachloroethylene are formed at a rate, which depends upon the acidity of the solution and its content of cupric ions. For simultaneously obtaining a high reaction rate and a satisfactory yield of triand tetrachloroethylene we prefer to work at a pH value of 1-2.5 and at a content of cupric ions which is Patented Jan. 31, 1967 ICC - 70-100 mole percent of the total copper content of the reaction solution. The most favorable range for the formation of t-richloroethylene seems to lie at 70-90, and

- for the formation of tetrachloroethylene at 85-100, calculated as mole percent cupric ions.

The reaction can be carried out batchwise as well as continuously.

It can be carried out in a conventional apparatus, for instance in a vessel with an agitator and a gas inlet, in a column, or a tube reactor. The reaction solution is charged in a reactor and the acetylene is introduced at a temperature of at least 60 C., suitably -130 C., in which case a pressure vessel is not needed. The reaction rate can be increased by increasing the temperature above C. and operating in a pressure vessel. The reaction rate can be further increased by supplying the acetylene at such a rate as to produce in the reaction chamber a pressure which is higher than the pressure of saturated steam at the reaction temperature. The cupric chloride is reduced to cuprous chloride While the acetylene is chlorinated. The reaction products gradually leave as vapours as they are formed.

Of a particular interest is the possibility to carry out the reaction continuously. It is then possible to use the range of the reaction, for instance between the cupric ion contents of 75-85 mole percent, where the reaction rate to the desired compound is largest. To make sure that the reaction compound by a possible cooling does not crystallize because of the precipitated cuprous chloride it is suitable to add chlorides of other metals, for instance potassium, sodium, lithium, magnesium, calcium. These additives in certain cases also have an activating efiect on the reaction. However, the additives limit the possibilities of working with very high copper chloride contents (more than 4 moles per liter). The latter may be desirable, when working continuously and in the range, where the cupric ion content in relation to the cuprous ion content is so high, that the formed cuprous chloride is held in solution by the chloride ions present. It is thus important for the technical realization of the reaction that the chloride ion content is high. Which cation to use for accomplishing this seems to be of a lesser importance.

In the following some examples of carrying out the reaction are described. The following abbreviations are used:

tri-=trichloroethylene tetra-=tetrachloroethylene 1,1-=1,1-dichloroethylene -cis-= cis-1,2-dichloroethylene trans-=trans-1,2-dichloroethylene rem. =remainder ent.=entering Example 1 500 ml. of a solution containing 255 g. (:15 moles) CuCl .2H O and 102 g. 1.5 moles) MgC1 .6H O were introduced in a one-litre retort provided with agitator, thermometer, gas inlet, tube and cooler. The retort was placed in a heat-bath for keeping the temperature at 98 C. during the reaction. Carbon dioxide was introduced for purging air out of the apparatus, Where- 'after the reaction was started by introducing acetylene (10 litres per hour). The pH of the solution was :23 at the start. (pH dropped to 0.9 during the reaction.) The formed reaction products and the distilled water was collected in a tube in a deep freeze-bath at -60 C. The test tube was exchanged each 15 or 30 minutes and the reaction products were Weighed and analyzed by means of a gas-chromatograph and an lR-spectrophotorneter. The results are listed in the following table.

tion was 1.8. At 120 C. and an absolute pressure of 2.4 atm. acetylene was injected into the solution, the

Formed Reaction products in percent Mole pe- Time interval, min. product, cent Cu g. at the end tritetra- 1,1- cistrans- Rem. of interval The total conversion of acetylene during the test was 70% and the yield of tri- 24% and of tetrachloroethylene 23%.

Example 2 This test was carried out in the same apparatus and in the same manner as in Example 1 but the reaction solution contained only 510 g. (:3 moles) CuCl .2H O. pH was 1.7 at the start. Acetylene was introduced at a rate of litres per hour. The test could only be continued to a degree of reduction of based on the amount of charged CuCl as at this degree of reduction CuCl starts to precipitate.

reducing valve being adjusted so as to release 1 litre gas per hour from the apparatus. After one hour 8.5 g. product was obtained in the condenser. The composition was 43% trichloroethylene, 2% tetrachloroethylene and trans-1,2-dichloroethylene. In a corresponding test at 90 C. and atmospheric pressure an amount of 3.3 g. of product was obtained having a composition of 59.3, 3.7 and 37.0%, respectively.

Example 4 This test was carried out with a continuous feed and removal of the reaction solution. The reaction vessel Formed Reaction products in percent Mole per- Time interval, min. product, cent Cu g. at the end tritetra- 1,1- eistrans- Rem. of interval 5. 55 48 32 1 0.1 13 7 88 12. 29 64 11 l 0. 1 12 13 75 13.83 53 1. 4 2 0. 1 29 14 12. 16 33 0.2 4 0. 1 46 17 ca. 55

The total conversion of acetylene during the test was 45% and the yield of trichloroethylene was 56% and of tetrachloroethylene 8%.

Example 3 The test Was carried out in a cylindrical container having a gas distributor in the bottom through which the acetylene was supplied and the leaving gases being passed from the top of the container to a condenser Where the reaction product was collected. After the condenser a manometer and a reducing valve were connected. In the container was charged 200 ml. Water solution conconsisted of a glass tube with a length of 660 mm. and a thickness of 50* mm. and having a heating coil. The acetylene was supplied through a gas distributor in the lower part of the vessel and the reaction products were allowed to distill off in the upper part of the tube. The fresh reaction solution was supplied at the bottom and the reacted solution flowed out through an over-flow in the middle of the tube. By controlling the supply rate of the solution and the acetylene amount (5 litres per hour) it was possible to obtain 500 ml. of the solution having a relatively constant degree of reduction in the vessel. The concentration of the solution was 3 moles CuCl per litre and 6 moles LiCl per litre. pH was :23.

The results are given in the table below:

I Reaction products in percent Mole percent Cu Time Formed interval, min. product,

g. tetra- 1,1- cis- Trans- Ent. sol. Outg. sol.

+rern.

taining 3 moles copper chloride and 6 moles lithium chloride per litre. 7 mole percent of the total copper amount was present as Cu (1) and the pH of the solu- The conversion of acetylene during the test was about 45 and the yield of trichloroethylene 66% and of tetrachloroethylene 10%.

Example 5 This test was carried out as in Example 4. Only 3 litres acetylene per hour was supplied and pH was =2.6

Principally, the apparatus consists of a reactor I having an inlet at the bot-tom for the chloride solution supplied from a container 311, an inlet for acetylene and an over-flow for the solution. The reaction product is dist th Shari; R lt 5 charged at the top of the reactor together with the un- Reaction products in percent Mole percent Cu Time Formed interval, min. product,

g. tritetra- 1,1- cis- Trans- Ent. s01. Outg. sol.

+rem.

4. 16 57. 1 40. 7 1 0. 92 3 93 5. 73 61.5 33. 2 1 0. 02 5 93 so 5. 90 67. 7 26. 9 1 0. 03 5 93 79 6. 13 69. 0 21. s 1 0. 03 9 93 76 5. 13 69. 0 20. 9 1 0. 03 19 93 76 E wg f ig i 22$ g i z z reacted gas and collected in a condenser 5. The used g 2 Owe yene 0 an 0 e we solution is passed to a container 6b from which it is at yene E l 6 pumped by a pump 4b to another container 3b. The

xamp 8 copper (I) ions in the used solution are oxidized with This test was carried out as in Example 3 but the over- HCl and O in an oxidation column 2 having an inlet at flow was elevated so that the reaction vessel contained 25 the bottom for the solution supplied from the container 750 ml. solution containing 6 moles CuCtl per litre. pH 3b and an over-flow from which the solution flows to was :26. a container 6a, the solution being pumped therefrom by The results are given in the table below: a pump 4a to the container 3a. The oxidizing gases (HCl Reaction products in percent Mole percent Cu Time Formed interval, min. product,

g. tritetra- 1,1- cis- Trans- Ent. s01. Outg. sol.

+rem.

I The conversion of acetylene during the test was and 0 are supplied into the column at the bottom and and the yield of trichloroethylene 65% and of tetrareleased at the top. chloroethylene 19%. In the formed retaction product Instead of using a separate oxidation column the retriand tetrachloroethylene are easily separated :by disoxidation may be carried out in a reactor provided with till ti Y separate inlets for acetylene and the mixture of oxygen Example 7 and hydrogen chloride. We claim In this test the volume of the reactor vessel was about 8 litres, the apparatus for the rest being principally the glethod for the productliqn mchloroe'thylene and same as in Examples 4-6. The water solution continuoustetra: loroetilyhaine by a 9 between iacfityiene and ly supplied contained 6 moles/litre copper chloride 8 Popper 'chtlonde m awatfl utlon t h mole percent of the total copper amount being present as mg acetylene h h a {caption solut1on. i tammg cupnc' cu (I) The PH of the S 01 ultion was L8 and its temperw and cuprous ions, 1n whlch the cupnc ions constitute ture 100 C. Acetylene was supplied at a rate of 20 mole percent of the l coppel mamnormal litres per hour and was converted to a product t-ainmg the pH-value of the reaction solut1on at 1 to 3 and consisting of 81% (by weight) of trichloroethylene, 12% g s g f g g of i lezlislo h tetrachloroethylene and 7% trans-dichloroethylene. The o accor 0 l i m W m total conversion acetylene was 97% chlorlde lOIl content in the solut1on is from 4 g.-atoms per litre up to a solut1on, which is saturated at the reaction Example 8 temperature. The test was carried out continuously as in Example M h hccordlhg clahh 1 in which the amount 7 but the Solution Contained 5 moles of copper ch:10 of tcupric ions 15 kept at 70-100 mole percent of the total ride and 3 moles of lithium chloride per litre. The copPeramountamount of Cu (I) was 15 mole percent of the total copper Method q to chum m which ihe solut1on amount the PH of the solution was L8 and its tempem besides copper chloride also contalns a water soluble chloture 100 C. 20 normal litres per hour of acetylene was ride f a f 'f selecte'fl from group cohslshhg of practically completely converted to a product consisting pftasslum, hthlum, calcium, magheslhm, ahl-mlnllm and of 76% (by weight) of trichlloroethylene, 12% tetra- Z1110 chloroethylene and 12% trans-dichloroethylene, in all 114 Method Id ng to claim 1 in which the solution g. per hour. The catalyzing solution was then pumped also contains ammonium chloride. to an oxidation column, where it was oxidized with a mix- 6. Method according to claim 1 in which the acetylene ture of about 60 normal l es of HC -gas and 30 normal is supplied at such a rate as to produce in the reaction lltfes of oXygeIl P chamber a pressure which is higher than the pressure The Process y h 'carr'led out h a larger scale m of saturated steam at the reaction temperature. an apparatus schemancally illustrated in the ac-companying drawing.

(References on following page) 7 References Cited by the Examiner UNITED STATES PATENTS 2,779,805 1/1957 Millard 260654 X 2,809,221 10/1957 Thomas et a1. 260654 2,915,565 12/1959 Jac'obow'ski et a1. 260-654 8 3,079,444 3/1963 Jacobowski et a1. 260654 3,184,514 5/1965 Sennewald e-t a1 260654 3,197,515 7/1965 Chassaing et a1 260654 LEON ZITVER, Primary Examiner.

K. V. ROCKEY, Assistant Examiner. 

1. METHOD FOR THE PRODUCTION OF TRICHLOROETHYLENE AND TETRACHLOROETHYLENE BETWEEN ACETYLENE AND COPPER CHLORIDE INA WATER SOLUTION, WHICH COMPRISES PASSING ACETYLENE THROUGH A REACTION SOLUTION CONTAINING CUPRIC AND CUPROUS IONS, IN WHICH THE CUPRIC IONS CONSTITUTE 50-100 MOLE PERCENT OF THE TOTAL COPPER AMOUNT, MAINTAINING THE PH VALUE OF THE REACTION SOLUTION AT 1 TO 3 AND A REACTION TEMPERATURE OF AT LEAST 60*C. 